In the beginning of the 1950's Sweden carried out some extensive AFV trials and developments. In 1953 Sweden was able to purchase 80 Centurions (strv 81 or "tank 81") from Great Britain and therefore the development work temporarily stopped, at least concerning the tank trials. Later on Sweden purchased additional Centurions to form the entire national tank fleet. However during the late 50's Sweden decided to pick up the trials where they had left them. Due to very thorough investigations and reports about recent conflicts (the main source of course being WW2) Sweden drew its own conclusions about how a future tank concept would look like. The main idea was to reduce the tanks frontal silhouette to a minimum and to give the crew maximum protection. According to hit probability analysis that Swedish engineers did, the hit probability increased with increased height of the vehicle and that it was 100% higher/ square inch in the turret than in the hull. So the solution was get rid of the turret! Several initial trial vehicles were built, amongst others a WW2 Sherman (bought from France after the war) which featured a fixed gun and a rebuilt running gear, this prototype was used to test aiming and gun traversing using only the tracks.
The result of these trials resulted in a very complicated hydraulic suspension system wich also incorporated the elevation and traverse of the main gun.
In 1959 "Bofors" (the well known Swedish ordnance manufacturer) got the order to build two main prototypes (S1 and S2) to "stridsvagn S" as it was called, S standing for Swedish. The prototypes were delivered in 1961 and later on 10 additional test vehicles (the "0" series) were delivered. In 1964 the Swedish government decided to purchase 290 tanks, the first in the series were delivered in 1967 and the last were delivered in 1971. The tank underwent two major rebuilds, the first in the middle of the seventies (strv 103B) and the second in the middle of the eighties (strv 103C). The "C" conversion added german Diehl tracks, laser range detector, new engines and additional protection, the most visible change being the "jerry can" rack on the sides.
Its main advantage was always the excellent 105 mm (though rifled) gun. The latest ammunition to be used had penetration nearly as good as contemporary 120 mm smoothbore guns. Another good feature was that both driver/gunner and the commander could both fire and drive the tank. In effect, if the reverse driver and the gunner/driver were put out of action the commander could still both "shoot´n scoot"!
The S-Tank was supposed to have good protection and with the engines and transmission in front of the crew thus serving as additional armour it did, at least in the 60's when it first was introduced. But when the T-72 arrived it became apparent that the protection needed to be improved. A steel "fence" was added to the front armour wich had some effect but when the T-80 appeared it was apparent that the protection was inadequate, to say the least!
In fact during the beginning of the 90's Sweden managed to get hold of some T-72's. The armour development section made some live firing tests against the "S" with them and the results were horrifying. Most of the rounds penetrated the frontal armour (through the steel "fence") smashed their way through the engines and crew compartement and ended their days in the ammunition stowage compartment, in the rear of the tank. NOT a very comforting surprise.
Another main disadvantage was that you couldn´t fire with any precision on the move! And with a fixed gun you couldn´t aim your gun at the most dangerous direction while on the move. Crucial, basic needs for any modern tank.
To add on the list of disadvantages the giant hydraulic system was both hazardous and posed a very serious firethreat. It was also prone to breaking down. The MTBF was appallingly short... (Mean Time Between Failures).
Today the "S" tank is no longer in service, the last conscripts to get training did so in 1996. It was decided to scrap the tanks but only when Sweden had aquired enough new tanks.This happened in the end of the 90's when Sweden purchased Leopard 2 A4 and A5 (the "Improved"). Recently the scrapping began and now (Jan 2000) the trains, loaded with tanks, are steadily rolling to the blast-furnaces.
Data:
Combat weight: 42.5 metric tons
Length: 8.99 metres
Width: 3.63 metres
Height: 2.14 metres ( turret roof)
Crew: 3, one commander, one driver/gunner and one "reverse driver" facing backwards, behind the driver/gunner.
Ground preassure: 104 kPa
Power/ weight ratio:18.4 hp/ton
Max speed: 50 km/ hour
Engines: 1 x Detroit diesel (6V-53T) mainly used to produce power for the hydraulic system.
1 x Caterpillar diesel gas turbine engine for the propulsion of the tank.
Total hp: 780 (the piston diesel: 290 hp and the gas turbine 490 hp)
Transmission: Volvo and Bofors, 3 automatic gears. The reverse utilizes the forward gears also so it as fast in reverse as in forward gear.
Hydraulics: contains 140 litres of HIGHLY flammable and VERY toxic hydraulic oil........
Armament:
1 x 105 mm main gun (the license built British L7 gun)
2 x fixed ksp 58 (the swedish licensebuilt MAG) in the hull.
1 x ksp 58 by the commander (which he can aim and fire independently from his seat)
2 x 71 mm flaremortars ("lyran"), the "S" had no thermal imaging sights or other modern observation devices.
8 x close proximity smoke dischargers fixed on the commanders cupola. (The commanders observation cupola was hydraulically powered and he could elevate and traverse it and fire the smoke and machinegun in any direction he saw fit.)
Ammunition:
105 mm APFSDS
105 mm HE
105 mm smokerounds for the main gun (a separate magazine manhandled by the reverse driver containing 5 rounds)
The main gun used an autoloader (located in the rear) containing up to 50 rounds . This worked very well and had loading times of about 3 seconds. To change ammunition you simply pressed a button. You could also fire in "automatic" mode (when for example you wanted to fire for effect with HE rounds). Thereby the system "locked" the elevation system giving it quite good precision. 1500 7,62 rounds for the machineguns (500 in each magazine).
Additional Sources:
ipmslondon.tripod.com
www.trackpads.com
de.academyhobby.com
afvid.topcities.com
www.foreningenp5.com
www.haaland.info
w1.500.telia.com
softland.com.pl
www.ifrance.com
www.army.lt
